Justin Bieber explains crying, sings country and performs 'What Do You Mean' on 'Tonight Show'

Justin Bieber took his comeback tour and potentially chart-topping single, "What Do You Mean," to The Tonight Show Starring Jimmy Fallon on Wednesday (Sept. 2).

Wearing an oversized camo jacket and black cap, the 21-year-old singer exuded calm confidence on the couch, joking with Fallon about their shared hatred for aerial harnesses ("It pulls on the junk!") and candidly discussing his emotional moment at the MTV Video Music Awards.

"I didn't expect them to support me in the way they did. Last time I was at an awards show, I was booed."
Justin Bieber

"It was so overwhelming," said Bieber. "I missed some cues so I was a bit disappointed about that. But just the support... I didn't expect them to support me in the way they did. Last time I was at an awards show, I was booed."

Bieber came off surprisingly genuine and unscripted, admitting that he was "ranting" at one point and even forgetting his own album release date (Nov. 13).

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Justin Bieber at the MTV VMAs

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Justin Bieber explains crying, sings country and performs 'What Do You Mean' on 'Tonight Show'

"I worked so hard at this album... at becoming the man I want to become and stepping into that situation, you just can't help but feel judged," he said. "I wanted to win so badly, I just put everything on the line. It was authentic and real... I was just wanting it so bad."

"Plus you did have that harness pulling on your..." Fallon offered to audience laughter.

Bieber acknowledged that he had made mistakes and surrounded himself with "knuckleheads," but argued that he was surrounded by ceaseless "spotlights and cameras" to record his every misstep.

"Don't laugh!" he berated the crowd with a grin. "You guys have those moments!"

"Not as many as you, Justin," Fallon quipped.

Bieber delighted the studio audience with a twanging country rendition of "What Do You Mean," as well as an attempt to replicate the famous "dolphin sound" -- which Skrillex created by pitching up Bieber's vocals -- from "Where Are U Now." Back in 2010, Bieber lost a drum-off with The Roots' Questlove, but the pop star held his own in a spirited rematch this time around.

Even when the cameras were off, Bieber remained fluid and engaging -- dancing along to The Roots' interim jams and greeting everyone onstage with exuberant hugs. Judging by the shrill screams, there were plenty of Beliebers in attendance. After the show, one even explained how she'd camped out on the street for 26 hours to ensure she got a seat.

Bieber's closing performance of "What Do You Mean," which is eyeing a possible Hot 100 debut, was a powerful reminder of the singer's undeniable charisma and vocal talent, while hearty backslaps with The Roots proved a valuable co-sign.